<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>return x+y 的值</title>
	</head>
	<body>
		<script>
			function add(x,y){
				return x+y;
			}
			var sum = add(5,5);
			alert(sum);
		</script>
	</body>
</html>
